High speed printer

ABSTRACT

A high speed, on-the-fly printer and method for operating same incorporating a type font having an increased number of character spaces for unit length of print line to increase printing speed for other established operating parameters. The printer has an unique hammer actuation assembly to facilitate the relatively small print character size without compromising hammer drive force.

United States Patent 11 1 Potter 1 Nov. 18, 1975 HIGH SPEED PRINTER [75]Inventor: John T. Potter, Locust Valley, NY.

[73] Assignee: Potter Instrument Company, Inc., Plainview, NY.

22 Filed: 0a. 5, 1973 21 Appl. No.: 403,909

[52] US. Cl 101/93.32; 101/9302 [51] Int. Cl. 1341.1 9/42 [58] Field OfSearch 101/93 C, 111

[56] References Cited UNITED STATES PATENTS 3,289,575 12/1966 Wassermann1(11/93 C 3,301,177 l/l967 Shepard 101/93 C 3,418,928 12/1968 Ponzano101/93 C 3,433,153 3/1969 Harrington et a1 101/93 C 3,585,927 6/1971Burns et a1 101/93 C 3,605,611 9/1971 Konkel et al 101/93 C 3,636,865l/1972 Konkel et a1... 101/93 C 3,640,217 2/1972 Drejza 101/93 C3,715,978 2/1973 Raider 101/93 C Primar i' ExaminerC1iff0rd D. CrowderAssistant ExaminerEdward M. Coven Attorney, Agent, or FirmLane, Aitken,Dunner & Ziems [57] ABSTRACT A high speed, on-the-fly printer and methodfor operating same incorporating a type font having an increased numberof character spaces for unit length of print line to increase printingspeed for other established operating parameters. The printer has anunique hammer actuation assembly to facilitate the relatively smallprint character size without compromising hammer drive force. 1

6 Claims, 8 Drawing Figures US. Patent Nov. 18, 1975 Sheet 1 0143,919,933

\ \eeexek INFORMATION CONTROL CIR CU ITRY US. Patent Nov. 18, 1975Sheet2 of4 3,919,933

U.S. Patent Nov. 18, 1975 Sheet30f4 3,919,933-

HIGH SPEED PRINTER BACKGROUND OF THE INVENTION This invention relates tomethods and apparatus for high speed printing and more particularly, itconcerns improvements in high-speed, on-the-fly line chain printers foruse in computer systems as well as unique methods'for operating suchprinters to improve speed and reduce paper consumption.

High speed printers are used extensively in computer systems to providea readable printed record of computer processed information. Suchprinters conventionally employ a continuously moving type fontselectively synchronized with a linear bank of electromagneticallyoperated print hammers located on the opposite side of paper to beprinted and a ribbon from the type font. In the printing operation, ahammer assigned to a particular character position is activated at anappropriate time to strike the paper and push it against a ribbon andthe particular character on the type font as the latter passes theposition of the hammer. Upon completion of each printed line, the paperis advanced for printing the next succeeding line. Two basic types ofsuch high speed, on-the-fly printers have been employed; that is, (1)drum printers in which the characters of the type font are carried onthe periphery of a continuously rotating drum thus to be located on thedrum in printing columns and and struck by the appropriate hammers atthe intersection of such columns and a line and (2) chain printers inwhich the type font is carried by an endless belt or chain, thecharacters moving in individual lines to be struck at the intersectionof such line and a column by the appropriate hammer.

The principal objection to drum printers is that because the typecharacter slugs are moving vertically in relation to the hammers, theslightest measure of improper synchronization between the hammers andthe type slug characters will result in vertical misalignment of thecharacters printed on the paper. Such misalignment is readily detectableand objectionable to one reading the printed copy. On the other hand, inchain printers, because the type font moves in a linear path parallel tothe hammer bank and the lines to be printed, the same measure ofnon-synchronization will result only in a non-detectable slightirregularity of spacing between the printed characters. In light of thisenhanced quality or legibility of printed matter, high speed, on-the-flychain printers are very much in demand.

Inasmuch as the speed of the computer system with which such printersare used is virtually unlimited, the time required to print outprocessed information remains a predominant limitation on overall systemspeed. In the context of printer operation, ultimate speed must bemeasured in terms of number of characters printed per unit time, afactor which depends primarily on the amount of time required to print asingle line in the present state of the art. In this respect, it isnoted that the increment of time required to shift the paper web betweensuccessive printing lines is unproductive time in terms of actuallyprinting characters. For this reason, it is conventional practice in theart to use relatively wide paper, for example, 14%inches which, withside margins for drive sprocket holes and the like will accommodate 132characters per line, using character spaces per inch. Such paper isusually supplied in continuous, accordion fold form, perforated andfolded at 11 inch intervals in what has been heretofore an effort tooptimize printing speed and manageability of printed material.

The speed at which each line is printed by a chain printer istheoretically governed by the length of time required to advance acomplete font of print over the length of the line. In the past, manydiverse types of print font carriers have been developed in an effort toadvance a font of type characters throughout the length 0 of the line tobe printed in the shortest possible time.

Irrespective of the print font carrier employed, such factors asmechanical friction and resulting heat, and accuracy of type slug travelin terms of linearity and spacing, for example, have had a limitingeffect on the linear velocity at which a type font may be advanced alongthe line to be printed. Although various types of chain printers havebeen operated in the past at speeds of between 1,000 and 2,000 lines perminute, each line conventionally including 132 character spaces, thecapacity of the computer system to operate at much higher speedsindicates a need for higher printer speeds.

SUMMARY OF THE PRESENT INVENTION In accordance with the presentinvention, the overall printing speed of an on-the-fly chain printer ismaterially increased over that of such printers heretofore available byreducing at least the lateral dimension of print character spaces to thesize of conventional text book print, thereby to reduce the distancethrough which a linear type font of printing characters must travel toprint a line with a given number of such character spaces. Specifically,the lateral dimension of each character space is selected to provide 14to 16 such spaces per linear inch, the printing operation at each suchspace being effected by an individual hammer constituting one of alinear bank of such hammers uniquely assembled for individualelectromagnetic actuation.

From the standpoint of structural arrangement, the invention is embodiedin a high-speed chain printer employing a print chain in which aplurality of printing slugs are carried on an elastomeric timing belt,each slug carrying a plurality of type characters as shown generally inUS. Pat. No. 3,621,778 issued to D. J. Ripple et al on Nov. 23, 1971. Anovel hammer bank assembly is provided to cooperate with such a printchain, the hammer bank employing an individual hammer corresponding toeach printing character space. Individual mounts for the relativelysmall hammers as well as a measure of space accommodation for a completeelectrogmagnetic firing assembly for each hammer is provided bysupporting and actuating alternate hammers'from opposite sides of acommon print line, thus to provide upper and lower tiers of hammerswhich are interlaced in the sense that impacting hammer heads of bothtiers are aligned with the print line. The interlacing of hammers inthis manner also enables the use of a precision machined slotted guideand abutment snubbing bar, one for each tier of hammers, and whichenables precise control over the movement of each hammer head onactuation.

The measure of space accommodation for individual and independent hammerfiring assemblies provided by the interlaced arrangement of hammers isfurther enhanced through the use of low inertia push rodinterconnections between the hammers and solenoid actuators. Moreparticularly, encased and freely floating piano wire push rods arearranged in upper and lower tiers corresponding respectively to theupper and lower hammer tiers. The lengths of the wires are staged sothat three rows of solenoid actuators may be employed in each tier, therows extending parallel to the print line. By virtue of thisarrangement, adjacent solenoid actuators in each row constitute theactuator for each sixth hammer. Hence, the electromagnetic poweravailable for actuation of each hammer is not compromised by the reducedsize and spacing of the hammers.

Among the principal objecives of the present invention are, therefore:the provision of high-speed, on-thefly printing method and apparatus bywhich the speed particularly of chain-type on-the-fly printers issignificantly increased over the printing speed of such printersheretofore available; the provision of such a printing method andapparatus which results in both improved printing speed and inconservation of paper or other printing medium; the provision of animproved impact hammer assembly for high-speed, on-the-fly printers ofthe type used in computer systems; the provision of such an impacthammer assembly which maximizes the electromagnetic force available forfiring each hammer for a small physical size and spacing of the hammers;and the provision of such an impact hammer assembly incorporatingprecision guide and/or snubbing means for each hammer.

Other objects and further scope of applicability of the presentinvention will become apparent from the detailed description to followtaken in conjunction with the accompanying drawings in which like partsare designated by like reference numerals.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an exploded perspective,partially schematic view illustrating the general organization of thechain printer of this invention;

FIG. 2 is a front elevation illustrating the hammer bank assembly of thepresent invention;

FIG. 2A is a greatly enlarged front elevation illustrating a portion ofthe hammer bank illustrated in FIG. 2 with chain carried type characterssuperimposed thereon in phantom lines;

FIG. 3 is an enlarged fragmentary cross-section taken on line 3--3 ofFIG. 2;

FIG. 3A is a still further enlarged fragmentary crosssection taken online 33 of FIG; 2;

FIG. 4 is a fragmentary cross-section taken on line 4-4 of FIG. 3;

FIG. 5 is an exploded perspective view illustrating the hammer actuatingpush rod support assembly for the printer of the present invention; and

FIG. 6 is an enlarged fragmentary plan view illustrating the hammerguide and abutment stop mechanism of the apparatus of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT In FIG. 1 of thedrawings, a chain printer embodying the present invention is generallyshown to employ a print chain of the type described in theaforementioned U.S. Pat. No. 3,621,778 and generally designated by thereference numeral 10. Accordingly, the print chain incudes a pluralityof multicharacter type slugs 12 carried on an endless timing belt 14trained about rotatably driven gears 16 and 18. As shown, each type slug12 carries on its front face three raised characters 20, the lateralcenter to center spacing of each character 4 on the chain beingdesignated by the reference letter T and discussed in more detail below.Although only three such type characters are shown in FIG. 1 of thedrawings, it will be appreciated by those familiar with the high-speedprinting art that the print chain will include one or more fonts of thetype characters around the complete length of the endless belt 14, eachfont v containing one of each character to be printed. Typically, a fontmight include forty-eight characters representing the 26 letters of theEnglish alphabet, ten numerals and twelve miscellaneous symbolsincluding punctuation marks and the like.

Also in accordance with conventional practice, an ink ribbon 22 ispositioned between the type characters 20 and a print receiving mediumconventionally in the form of a continuous paper web 24. On the oppositeside of the paper web and ribbon from the type characters 20 ispositioned a linear bank of hammers 26, 28 each having a head 30 adaptedto be advanced against the paper 24, the ribbon 22 and the typecharacters 20 so that the paper 24 will receive a printedimage of thetype character struck by any one of the several hammer heads.Conventional operation of such printers involves the feeding ofinformation by a computer designated by the reference numeral 32 tocontrol circuitry 34 of the printer operative to fire any one of aplurality of actuating solenoids 36 to cause a particular hammer toimpact the paper, the ribbon, and the type character through linkagemeans to be described in more detail below. The control circuitry 34 ofthe printer also incorporates means for correlating the precise locationof each type character 20 precisely with the location of any one of thehammer heads 30 at all times while the chain 10 is being drivencontinuously at high linear velocities. Inasmuch as one hammer head 30is provided for each character space along a line to be printed on thepaper web 24, printing of a particular character at a specific characterspace along the line involves an impacting of the hammer headcorresponding to that space at the instant the type character desired tobe printed passes that space. Since a complete printing capabilityrequires a facility for any one of the type characters 20 to beimpressed against the paper at any character space position along thelength of a line to be printed on the paper, the shortest time in whicha line can be printed is the time required for a complete font of thetype characters 20 to traverse the line. An important feature of thepresent invention results from a foreshortening of the character spacewidth which in turn results in a corresponding foreshortening of a fontof such characters as well as a foreshortening of the length of the lineprinted on the paper web 24, assuming a given number of character spacesper line.

To provide a clear understanding of the interrelation of the hammerheads 30, the chain carried type characters 20, and a line of printedcharacters on the web 24, reference is made to FIG. 2A of the drawingsin which these items are schematically superimposed. Specifically, thewidth of each printed character space is designated by the referenceletters S, such printed character spaces being adjacent to one anotherin each line to be printed. The hammer heads 30 on the respectivehammers 26 and 28 are disposed on a common horizontal center line XXwhich corresponds to the location of the line to be printed on the web24 during the time such line is printed. The center-to-center spacing ofthe hammer heads 30 is designated by the reference letter H. Inasmuch asone hammer is provided for each printed character space, the dimension His equal to the dimension S or the width of the character space. Thecenter-to-center spacing of the type characters 20 carried on the chainis designated in FIG. 2A by the reference letter T and is larger thaneither of the dimensions S or H. Specifically, the dimension T exceedsthe dimension H by a multiple known in the high-speed printing art asthe aspect ratio, the multiple typically being 1.5. The reason for theaspect ratio is that because the paper web 24 and ribbon 22 are movedagainst an individual type character on the chain 10 by the individualhammer heads 30, a spacing of the type characters 20 on the chain equalto the spacing of the hammers and the printed character spaces S islikely to cause ghosting which is an unwanted partial printing of thetype character adjacent to the one intended to be impacted by aparticular hammer.

The increased printing speed resulting from the practice of the presentinvention without changing other printing operating parameters such asthe aspect ratio or the linear velocity of the print chain 10 may now beappreciated. Traditionally, chain printers have employed approximatelyten character spaces per printed line inch thus requiring 4.8 times 1.5(the aspect ratio) or 7.2 inches of chain length for each forty-eightcharacter type font. By reducing the character spacing S to conventionaltext book size on the order to 14 to 16 character spaces per inch of 15characters per inch, for example, the same type font occupies a lengthon the chain 10 of 4.8 inches. It will be appreciated therefore that thelength of time required for a forty-eight character type font totraverse each hammer in a chain printer operating in accordance with thepresent invention where fifteen character spaces are provided for eachlinear inch is less than the traditional chain printer by a factor ofone third where are all other operating parameters remain constant.Stated differently, the time of print font traverse is reduced toprovide a printing speed increase of 50% as compared with prior chainprinters.

The reduction of character space width and resulting increase printingspeed is attainable in substantial measure as a result of a novel hammerbank assembly depicted schematically in FIG. 1 and illustrated in moredetail in FIGS. 2-6 of the drawings. As shown most clearly in FIGS. l-3of the drawings, each of the hammers 26, 28 is identically constructedto include a pivot boss 38 at one end and having a bearing aperture 40for receiving a pivot pin 42 or 43. An arm or body portion 44 extendsfrom the pivot boss 38 to the hammer head and is provided with anenlarged push rod abutment 46 intermediate its length. A return springtang 48 projects from the pivot boss 38 in a direction opposite from thearm 44. A portion of the arm 44 extends rearwardly and beyond the head30 as an abutment tang 50.

As shown most clearly in FIGS. 1 and 2, the hammers 26 are pivoted fromthe pivot pin 42 carried by an upper hammer pivot block 52 fixedlysecured to such as by screws 53 to an upper mounting bar 54 forming partof a frame 55. As such, the hammers 26 depend from the upper mountingbar 52 as an upper tier of hammers. The hammers 28 constitute a lowertier of hammers and are pivoted from the pin 43 in generally upstandingrelation from a lower pivot block 56 similarly secured to a lowermounting bar 57. The heads 30 of both tiers of hammers 26 and 28converge on the common print line XX (FIG. 2) with the hammers 26 in theupper tier occupying alternate character space 6 locations with thehammers 28 in the lower tier. The hammers 26 are thus interlaced withthe hammers 28.

As shown most clearly in FIGS. 2, 3 and 3A, the print blocks 52 and 56are precision formed to nest against the mounting bars 54 and 57respectively and further, several such pivot blocks, each supportingmultiple hammers 26, 28 are mounted in side-by-side relation along thelength of each mounting bar. Also the pivot boss 38 of each hammer isreceived in one of multiple, uniformly spaced machined slots 58 havingrespective lateral dimensions or widths to receive the hammer bosseswith close tolerances and thus support the hammers for movement insingle pivot planes. The hammers 26 and 28 are biased to a retractedposition by helical compression springs 59 contained in appropriateborings 60 in the base of each slot 58 of the respective pivot blocks 52and 56.

Movement of each hammer from its retracted position to its impacting orstriking position is both further guided and limited by upper and lowersnubbing bars designated generally by the reference numerals 61 and 62,respectively and shown most clearly in FIGS. 3 and 6 of the drawings.Each of the snubbing bars is of L- shaped cross-sectional configurationto establish an elongated horizontal leg or base plate portion 64 and arelatively short vertical leg portion 66. A series of precisely machinedslots 68 extend through the leg portion 66 into the base portion 64 andare dimensioned to receive the portion of the hammer arm 44 between thepush rod abutment 46 and the head 30. The configuration of each snubbingbar, therefore, may be likened to that of a comb having teeth separatedby the slots 68 as seen in FIG. 6 of the drawings. Secured on the insidesurface of each vertical leg 66 is an abutment cushion 70 for engagementby the abutment tangs 50 on the re spective hammers 26 and 28.Specifically, and as shown in FIG. 3 of the drawings, the lower snubbingbar 62 is oriented along the length of the hammer bank such that theslots 68 therein are aligned to receive the lower tier of hammers 28.Similarly, the upper snubbing bar 61 is oriented so that the slots inthe upper bar receive the upper tier of hammers 26. Because of theinterlaced organization of the upper and lower tiers of hammers, theabutment pads 70 in the upper guide bar 61, being located intermediatethe slots 68, will be in a position to be engaged by the abutment tangs50 on the lower tier of hammers 28. In like manner, the abutment stopsor cushions 70 on the lower snubbing bars 62 are positioned to beengaged by the abutment tangs 50 on the upper tier of the hammers 26.Using the comb analogy in describing the arrangement of the upper andlower snubbing bars 61 and 62, it will be apparent that the teeth of theupper comb are positioned opposite the slot of the lower comb and viceversa, the abutment stops 70 being on the inner surfaces of the teeth.The retracted or rearwardmost position of the hammers 26 and 28 isestablished by a common cushion block 72 secured between the upper andlower snubbing bars 61 and 62 as shown in FIG. 3 of the drawings. Thusit will be seen that in spite of the relative small size of the hammers26 and 28, positive control is effected for the movement of eachindividual hammer by the relatively simple organization of the guidebars 61 and 62 together with the return stop block 72, all of which areadaptable to precision forming by readily available manufacturingtechniques. Further, these components are readily supported on a centralmounting bar 74 extending the length of the frame 55 and locatedcentrally between the hammer mounting bars 54 and 57.

As above indicated, the drive solenoids 36 are actuated during printingon command by the control circuitry 34 to advance the hammers 26 and 28forwardly at impact velocities until the abutment tangs 50 engage theabutment pads 70, at which time the face of the hammer head 30 willimpress the paper 24 and ribbon 22 against a selected type carrier 20.The solenoids 36 therefore, which must be equal in number to the numberof hammers 26 and 28, must also be sufficiently large in size to developan adequate electromagnetic force to effect this substantiallyinstantaneous movement of the hammers against the paper, the ribbon andthe type characters while the latter are travelling at high linearvelocity in a direction normal to hammer movement. The manner in whichthe spacial requirements for adequately powerful solenoids is met, aswell as the structural organization by which the solenoids are driveablyconnected to each of the closely spaced and relatively small hammers 26and 28 in accordance with this invention, may be understood by referenceto FIGS. 1 and 3-5 of the drawings. In addition to a solenoid 36,associated with each hammer 26 and 28 is a low-inertia push rod 76preferrably formed of piano wire and having plungers 78 and 79 atopposite ends. The push rods are supported in an assembly to bedescribed in more detail below such that the plunger 78 at the forwardend thereof is positioned to engage the plunger abutment 46 on eachhammer whereas the rear plunger 79 is adapted to be engaged by asolenoid actuated striker 80 also to be described.

As shown in FIGS. 3-5, the push rods 76 are supported in upper and lowertiers for actuation respectively of the upper and lower tiers of hammers26 and 28 by a series of adjacent plate assemblies 81 and 82cantilevered rearwardly from the upper and lower mounting bars 54 and57, respectively. Each such mounting plate assembly, as seen mostclearly in FIG. 5, includes a grooved plate 84, a cover plate 86 and asupport plate, all of such plates being secured together in overlyingcoextensive relation by screws 90. The assembly of plates 84, 86 and 88is further secured by mounting screws 92 which extend through the threeplates and into the respective hammer mounting bars 54 and 57 to securethe cantilevered support of the plate assemblies 81 and 82 in the mannerillustrated in FIG. 3. To locate the plate assemblies 81 and 82precisely in relation to the hammers, the surfaces of the upper andlower mounting bars 54 and 57 are provided with accurately machinepositioning grooves (not shown). The plate 84, as seen in FIGS. 4 and ofthe drawings, is provided with a pair of locating lugs 94 and 96 which,when assembled, extend upwardly through cut-outs 97 and 98 in the coverplate 86 to engage in the mounting plate grooves and thus position eachof the push rod supporting plate assemblies 81 and 82.

The plate 84 is provided with equally spaced push rod receiving grooves100a, 100b and 1006 which differ only in length or in the distance theyextend from the front edge 102 of the plate. It will be appreciated thatin the assembled supporting plates 81 and 82, the grooves 100 as well asthe push rods 76 therein will be enclosed by the cover plate 86 so thatthe push rods are supported along their length in Bowden wire fashion.

i The push rods 76 as may be seen in FIGS. 3 and 4 for example, are alsoof three different lengths in correspondence to the lengths of thegrooves 100a, 100b and C. Each of the grooves 100a and 10012 terminateat their rearward end in elongated slots 104a and 104b, respectivelywhereas the grooves 100C extend through the rear end 106 of the plate84. The lengths of the push rod 76 correspond to the lengths of thegrooves 100a, 1001) and 1000 such that the rear striker plunger 79 oneach third push rod will be located respectively in the slots 104a, 104band behind the rear end of the plate 106. Thus, the striker plungers 79in each tier of push rods are aligned in three rows extending in adirection parallel to the hammers. Because of the interlaced upper andlower tiers of hammers 26 and 28 and corresponding upper and lower tiersof push rods, the lateral spacing between each push rod in each tier, orthe lateral spacing between the grooves 100, is twice the center tocenter distance between hammers. By staging the lengths of the push rodsin the manner aforementioned, the rear plunger on each push rod to beengaged by striker 80 is spaced at three times the distance each pushrod is spaced or six times the center to center distance betweenhammers. Correspondingly, the lateral space available for each solenoid36 is six times the spacing between hammers.

The physical arrangement of the solenoids 36 in the printer may beunderstood by reference to FIGS. 3 and 4 of the drawings. As shown inFIG. 3, the chassis 55 incorporates a pair of upper and lower rearwardlyextending plates 110 and 112 preferably perforated for the circulationof cooling air therethrough. Each of the plates 110 and 112 are formedwith three inwardly facing grooves 114 extending in parallel with theline of hammers 26 and 28 and spaced correspondingly to the spacing ofthe three rows of striker plungers 79 on the push rods 76. The grooves114 receive spacer bars 1 16 on which a plurality of solenoid actuatingassemblies 118 are mounted. Each of the solenoid actuating assemblies118 includes a vertically oriented bracket 120 supporting a solenoid 36in operative relation to a corresponding striker 80. The strikers arepivoted from axes 122 and operate between the confronting end face ofeach solenoid 36 and a return stop 124 on the bracket 120. The end ofthe strikers 80 engage the striker plungers 79 on the push rods asshown.

In operation, the paper web is incrementally advanced and printed lineby line, the printing of each line being effected by the appropriatehammer head 30 striking the paper and ribbon 22 against a particularprint character as that character flies by the hammer. Although thisoperation, in itself, is well-known in the operation of chain printers,the time required to print each line in accordance with the presentinvention is significantly reduced by the reduction of the characterspacing S and the corresponding reduction in the distance each character20 must be moved in the overall printing operation.

Hammer striking actuation is initiated by the control circuitry 34 toenergize a solenoid 36 at the precise time interval such that thecorresponding hammer head 30 moves against the selected type character20 as it moves past the space occupied by the hammer head. Uponenergization, the solenoid fires the associated striker 80 against theplunger 79 to move the corresponding push rod 76 axially against theboss 46 on the hammer 26, 28 to pivot the hammer against the bias of thereturn spring 59 until the tang 50 engages the cushion 70 alignedtherewith. Return of the hammer and the push rod is effected by thespring 59. This essentially instantaneous movement of the push rod andhammer is possible largely because of the free axial support of the pushrods 76 in the supports 81, 82 and the low inertia of both the push rodsand the hammers. Moreover, there is not detectable difference in theoperation of hammers actuated by push rods supported in the relativelylong grooves 1000 as compared with those, relatively shortpush rods inthe grooves 100a.

Thus it willbe seen that as a result of the present invention, animproved high-speed printing method and apparatus is provided by whichthe above mentioned objects are completely fulfilled. It will beapparent to those skilled in the art that various modifications and- /orchanges can be made in the invention as described herein without in anyway departing from the true spirit and scope of the present invention.It is expressly intended therefore that the foregoing description isillustrative of preferred embodiments only, not limiting, and that thetrue spirit and scope of the present invention be determined byreference to the appended claims.

I claim:

1. A high-speed, on-the-fly chain printer comprising:

means supporting a linear font of printing characters for continuousmovement in a linear path parallel to a line to be printed on aflexible'print receiving medium;

a linear bank of individually actuatable hammers,

each hammer being operable to strike the print receiving medium againstany one of said printing characters as same passes such hammeron-the-fly, there being at least fourteen of said printing charactersand at least fourteen of said hammers for each linear inch of said fontand said bank, respectively;

including independent actuating each of said hammers;

wherein said actuating means comprises a plurality of low inertia pushrods each having a hammer end for engaging each of said hammers and anopposite striker end, means supporting said push rods intermediate saidends in at least one common plane for independent free axial movement inthe direction of hammer striking movement, the axes of said push rodsthereby being in parallel spaced interrelation, said push rods in saidone common plane also being of at least three different lengths andarranged so that the hammer ends of all push rods are laterally alignedand so that the striker ends of each third push rod are in lateralalignment, and drive means to engage the striker end of each of saidpush rods, said drive means being arranged in three lateral rows spacedat increments from the line of said hammer bank by a distancecorresponding to the lengths of said push rods, the center to centerdistance between each drive means in each row being three times thespacing between push rods in said common plane;

wherein said linear bank of hammers comprises interlaced upper and lowerhammer tiers, the hammers in said upper tier having heads depending froma common upper pivotal axis and the hammers in said lower tier havingheads upstanding from a common lower pivotal axis, the heads of saidupper and lower hammer tiers being successively alternated in saidlinear bank so that the center to center spacing between the hammers ineach tier is twice that of like spacing in said bank, said push rodsalso being arranged in upper and lower planar means for operating 10tiers to engage the respective hammers in said hammer tiers intermediatesaid heads and said common pivot axes, whereby the spacing of said pushrods in each of said planar tiers is also twice the center to centerspacing between said hammer heads in said linear bank; and comprisingsnubbing means for limiting striking movement of said hammers towardssaid printing characters, said snubbing means comprising means definingan abutment surface spaced beyond the head end of each of said hammers,each of said hammers having an abutment tang projecting beyond andpresented behind said head thereby to engage said abutment surface uponactuation of said hammers; wherein said snubbing means comprises upperand lower bars each being formed having slots to receive portions ofsaid hammers between the heads thereof and said pivotal axesrespectively, said abutment surface for engagement by said tangs on saidupper tier hammers being located between said slots on said lower barand said abutment surface for engagement by said tangs on said lowertier hammers being located between said slots on said upper bar. 2. Ahammer supporting and actuating apparatus for high-speed, on-the-flyprinters adapted to print at least fourteen character spaces in eachinch of printed line, said apparatus comprising;

a linear bank of hammers, each of said hammers having a headdimensioned'to cover the area of each such character space; means forsupporting said hammers in upper and lower hammer tiers, the heads ofsaid upper hammer tier being interlaced and laterally aligned with theheads of said lower hammer tier; independent means for actuating each ofsaid hammers to advance said heads from a retracted inactive position toan extended striking position, said actuating means comprising, upperand lower tiers of linear push rods each having a hammer end and astriker end, said push rods being of three different lengths andarranged so that the striker end of each third rod in each tier islaterally aligned in one of three rows whereas the hammer ends of allpush rods are laterally aligned,

a solenoid operated striker for each of said push rods, and

means for supporting said strikers in upper and lower tiers and in threerows in each tier corresponding to the rows established by the strikerend of each third push rod;

wherein said means for supporting said hammers includes upper and lowerpivotal supports for said upper and lower hammer tiers respectively, andincluding further, snubber means for cushioning movement of said hammersto said striker postion;

and wherein said hammers each include an abutment tang projecting beyondand behind said head and wherein said snubber bars are formed havingslots to receive the hammers of said respective upper and lower tiers,said cushioning means being located between said slots in a position tobe engaged by the hammers received in slots of the other one of saidbars.

3. A hammer supporting and actuating apparatus for high-speed,on-the-fly printers adapted to print at least 14 character spaces ineach inch of printed line, said apparatus comprising:

a linear bank of hammers, each of said hammers having a head dimensionedto cover the area of each such character space; a

means for supporting said hammers in upper and lower hammer tiers, theheads of said upper hammer tier being interlaced and laterally alignedwith the heads of said lower hammer tier;

independentmeans for actuating each of said hammers to advance saidheads from a retracted inactive position to an extended strikingposition and;

snubber means for cushioning movement of said hammers to said strikingposition, said snubber means comprising upper and lower snubber barseach having slots to receive the hammers of said upper and lower hammertiers respectively and each also having cushioned stops between saidslots for engagement by the hammers of said lower and upper hammer tiersrespectively.

4. The apparatus recited in claim 3 wherein said snubber bars are ofL-shaped configuration in a crosssectional plane normal to the line ofsaid hammer bank thereby to establish a horizontal mounting leg portionand a vertical abutment leg portion, said slots extending through saidabutment leg portion and into said mounting leg portion.

5. The apparatus recited in claim 4 wherein said cushion stops compriseelastomeric cushions bonded to the inside of said abutment leg portions.

6. In a high-speed on-the-fly chain printer comprising in combination;

an endless timing belt carrying a plurality of contiguous characterslugs;

means for moving said belt at a predetermined speed to progress saidcharacter slugs along a printing line; Y

a plurality of printing hammers arranged along said printing line and inopposition to said character slugs;

means for supporting a flexible print receiving medium between saidslugs and said hammers;

the improvement which comprises:

means for pivoting alternate hammers on an axis parallel to and abovesaid printing line;

means for pivoting the remaining hammers on an axis parallel to andbelow said printing line;

hammer actuating magnets arranged in parallel rows three deep andactuating said hammers through three different lengths of push rods toactuate said upper pivoted hammers and similar but inverted magnets andcorresponding push rods for actuating said lower pivoted hammers;

means including upper and lower combs comprising teeth and slots, theteeth of the upper comb being positioned opposite the slots of the lowercomb, the slots in the upper comb being adapted to guide the upperpivoted hammers along planes perpendicular to said printing line, theslots in the lower comb being adapted to guide the lower pivoted hammersalong planes perpendicular to said printing line;

wherein each of said hammers includes an abutment means and the innersurfaces of said teeth of said combs carry elastomeric snubbing means;

and wherein the abutment means of said upper pivoted hammers are adaptedto strike the snubbing means carried by the teeth of the lower comb andthe abutment means of said lower pivoted hammers are adapted to strikethe snubbing means carried by the teeth of the upper comb."

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION patent 3 ,919 ,933Dated November 18 1975 Inventor(s) It is certified that error appears inthe above-identified patent and that said Letters Patent are herebycorrected as shown below:

On the cover sheet Itein [75] should read Inventors: John T. Potter,Locust Valley;

John Tschinkel Great Neck, and

Henry Stalzer, Floral Park, N. Y.

Signed and Sealed this Second Day Of November 1976 [SEAL] Arrest:

RUTH C. MASON C. MARSHALL DANN Arresting Officer Commissioner uj'latenrsand Trademarks

1. A high-speed, on-the-fly chain printer comprising: means supporting alinear font of printing characters for continuous movement in a linearpath parallel to a line to be printed on a flexible print receivingmedium; a linear bank of individually actuatable hammers, each hammerbeing operable to strike the print receiving medium against any one ofsaid printing characters as same passes such hammer onthe-fly, therebeing at least fourteen of said printing characters and at leastfourteen of said hammers for each linear inch of said font and saidbank, respectively; including independent actuating means for operatingeach of said hammers; wherein said actuating means comprises a pluralityof low inertia push rods each having a hammer end for engaging each ofsaid hammers and an opposite striker end, means supporting said pushrods intermediate said ends in at least one common plane for independentfree axial movement in the direction of hammer striking movement, theaxes of said push rods thereby being in parallel spaced interrelation,said push rods in said one common plane also being of at least threedifferent lengths and arranged so that the hammer ends of all push rodsare laterally aligned and so that the striker ends of each third pushrod are in lateral alignment, and drive means to engage the striker endof each of said push rods, Said drive means being arranged in threelateral rows spaced at increments from the line of said hammer bank by adistance corresponding to the lengths of said push rods, the center tocenter distance between each drive means in each row being three timesthe spacing between push rods in said common plane; wherein said linearbank of hammers comprises interlaced upper and lower hammer tiers, thehammers in said upper tier having heads depending from a common upperpivotal axis and the hammers in said lower tier having heads upstandingfrom a common lower pivotal axis, the heads of said upper and lowerhammer tiers being successively alternated in said linear bank so thatthe center to center spacing between the hammers in each tier is twicethat of like spacing in said bank, said push rods also being arranged inupper and lower planar tiers to engage the respective hammers in saidhammer tiers intermediate said heads and said common pivot axes, wherebythe spacing of said push rods in each of said planar tiers is also twicethe center to center spacing between said hammer heads in said linearbank; and comprising snubbing means for limiting striking movement ofsaid hammers towards said printing characters, said snubbing meanscomprising means defining an abutment surface spaced beyond the head endof each of said hammers, each of said hammers having an abutment tangprojecting beyond and presented behind said head thereby to engage saidabutment surface upon actuation of said hammers; wherein said snubbingmeans comprises upper and lower bars each being formed having slots toreceive portions of said hammers between the heads thereof and saidpivotal axes respectively, said abutment surface for engagement by saidtangs on said upper tier hammers being located between said slots onsaid lower bar and said abutment surface for engagement by said tangs onsaid lower tier hammers being located between said slots on said upperbar.
 2. A hammer supporting and actuating apparatus for high-speed,on-the-fly printers adapted to print at least fourteen character spacesin each inch of printed line, said apparatus comprising; a linear bankof hammers, each of said hammers having a head dimensioned to cover thearea of each such character space; means for supporting said hammers inupper and lower hammer tiers, the heads of said upper hammer tier beinginterlaced and laterally aligned with the heads of said lower hammertier; independent means for actuating each of said hammers to advancesaid heads from a retracted inactive position to an extended strikingposition, said actuating means comprising, upper and lower tiers oflinear push rods each having a hammer end and a striker end, said pushrods being of three different lengths and arranged so that the strikerend of each third rod in each tier is laterally aligned in one of threerows whereas the hammer ends of all push rods are laterally aligned, asolenoid operated striker for each of said push rods, and means forsupporting said strikers in upper and lower tiers and in three rows ineach tier corresponding to the rows established by the striker end ofeach third push rod; wherein said means for supporting said hammersincludes upper and lower pivotal supports for said upper and lowerhammer tiers respectively, and including further, snubber means forcushioning movement of said hammers to said striker postion; and whereinsaid hammers each include an abutment tang projecting beyond and behindsaid head and wherein said snubber bars are formed having slots toreceive the hammers of said respective upper and lower tiers, saidcushioning means being located between said slots in a position to beengaged by the hammers received in slots of the other one of said bars.3. A hammer supporting and actuating apparatus for high-speed,on-the-fly printers adapted to print at least 14 character spaces ineach inch of printed line, said apparatus comprising: a linEar bank ofhammers, each of said hammers having a head dimensioned to cover thearea of each such character space; means for supporting said hammers inupper and lower hammer tiers, the heads of said upper hammer tier beinginterlaced and laterally aligned with the heads of said lower hammertier; independent means for actuating each of said hammers to advancesaid heads from a retracted inactive position to an extended strikingposition and; snubber means for cushioning movement of said hammers tosaid striking position, said snubber means comprising upper and lowersnubber bars each having slots to receive the hammers of said upper andlower hammer tiers respectively and each also having cushioned stopsbetween said slots for engagement by the hammers of said lower and upperhammer tiers respectively.
 4. The apparatus recited in claim 3 whereinsaid snubber bars are of L-shaped configuration in a cross-sectionalplane normal to the line of said hammer bank thereby to establish ahorizontal mounting leg portion and a vertical abutment leg portion,said slots extending through said abutment leg portion and into saidmounting leg portion.
 5. The apparatus recited in claim 4 wherein saidcushion stops comprise elastomeric cushions bonded to the inside of saidabutment leg portions.
 6. In a high-speed on-the-fly chain printercomprising in combination; an endless timing belt carrying a pluralityof contiguous character slugs; means for moving said belt at apredetermined speed to progress said character slugs along a printingline; a plurality of printing hammers arranged along said printing lineand in opposition to said character slugs; means for supporting aflexible print receiving medium between said slugs and said hammers; theimprovement which comprises: means for pivoting alternate hammers on anaxis parallel to and above said printing line; means for pivoting theremaining hammers on an axis parallel to and below said printing line;hammer actuating magnets arranged in parallel rows three deep andactuating said hammers through three different lengths of push rods toactuate said upper pivoted hammers and similar but inverted magnets andcorresponding push rods for actuating said lower pivoted hammers; meansincluding upper and lower combs comprising teeth and slots, the teeth ofthe upper comb being positioned opposite the slots of the lower comb,the slots in the upper comb being adapted to guide the upper pivotedhammers along planes perpendicular to said printing line, the slots inthe lower comb being adapted to guide the lower pivoted hammers alongplanes perpendicular to said printing line; wherein each of said hammersincludes an abutment means and the inner surfaces of said teeth of saidcombs carry elastomeric snubbing means; and wherein the abutment meansof said upper pivoted hammers are adapted to strike the snubbing meanscarried by the teeth of the lower comb and the abutment means of saidlower pivoted hammers are adapted to strike the snubbing means carriedby the teeth of the upper comb.